Detectors for third-generation X-ray computed-tomography scanners have a multiplicity of detector elements for detection of X-ray radiation. The detector elements are generally provided with a detector housing, which surrounds them, for protection. The detector housing may be formed integrally or may be composed of a plurality of separate housing walls.
Detector elements are provided in the detector housing and may comprise electronic circuits for processing signals from the detector elements. As the number of detector elements increases, they are arranged ever more densely and cause not inconsiderable heat losses during operation. This results in heating, and temperature fluctuations, in the detector housing and, as a result of this, in the detector elements. The temperature fluctuations lead to parameter changes and contribute to the creation of image artifacts.
In order to cool the interior of the detector housing, in particular of the detector elements and of the circuits, it is known, for example, for a cooling air flow through the detector housing to be produced by way of a fan provided on the detector housing. The fan admittedly makes it possible to largely avoid fluctuations in the cooling power and the temperature in the detector housing. However, this has the disadvantage that the life of the fan is reduced considerably as a result of the centrifugal forces and torques which occur during rotation of the detector about a rotation center of the X-ray computed-tomography scanner.
Instead of the fan provided on the detector housing, inlet and outlet openings can also be provided in the housing walls of the detector housing, through which a directed air flow can be passed by means of an external, stationary fan. This has the disadvantage that temperature fluctuations in the detector housing during operation of the computed-tomography scanner cannot reliably be avoided.